Speckle imaging for monitoring the growth kinetics of Bacillus thuringiensis

This paper presents an application of laser speckle imaging method to characterize the kinetic growth of Bacillus thuringiensis (Bt). Numbers of parameters, such as speckle grain size and spatial contrast, are considered in order to characterize the culture medium and to monitor in real time the fermentation process. We show that the grain size and the contrast of the speckle image decrease with the increase of the cells concentration. The correlation of speckle results with optical density measurements shows the effectiveness of dynamic speckle for real-time monitoring of Bt cells growth kinetics.